A mate of mine has/had a 500 3" that Ron Webb built on Red Label action. 12 guage I would suggest.

I also remember Ron had a Mini 14 that he converted into .308 1 1/2" and a 10/22 he'd redone to a Mannlicher stock.

A fella I knew had a Ruger 44 carbine that Webby also converted to a takedown.